Engineering Service Oriented Applications: From StPowla Processes to SRML Models

Service Oriented Computing is a paradigm for developing software systems as the composition of a number of services. Services are loosely coupled entities, can be dynamically published, discovered and invoked over a network. The engineering of such systems presents novel challenges, mostly due to the dynamicity and distributed nature of service-based applications. In this paper, we focus on the modelling of service orchestrations. We discuss the relationship between two languages developed under the Sensoria project: SRML as a high level modelling language for Service Oriented Architectures, and StPowla as a process-oriented orchestration approach that separates core business processes from system variability at the end-user’s level, where the focus is towards achieving business goals. We also extend the current status of StPowla to include workflow reconfigurations. A fundamental challenge of software engineering is to correctly align business goals with IT strategy, and as such we present an encoding of StPowla to SRML. This provides a formal framework for StPowla and also a separated view of policies representing system variability that is not present in SRML.